Hi, 94 E320 keeps running when the key is turned off. The history: 2 years ago new factory engine wiring harness, has been fine until last week. Last week while driving there was a strong smell of sulfur and gassing from the battery, disconnected battery cable while engine running and drove another 20 minutes just fine. Park the car and turned off the ignition took out the key and engine still running, I pulled the fuel pump relay to kill the engine, no lit warning lights on dash. Next relay back in, disconnected alternator wires to see if it was back feeding ignition, started engine and turn off key engine stiil running, pulled battery cable to kill engine. Last start engine and reach behind dash and unplug ignition switch, engine still running.

Where can the ignition be getting power ? I suspect the alternator is overcharging and melted something.

StillRunning

PING !

any help ?

Possibly the ignition switch itself.
Gilly

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Gilly, Thanks but I pulled the wires to the switch while the engine was running and it is still running.

Slewman

OK, I'd recommend doing the same thing again, then use a test light or multimeter and see which socket has power running to it, i believe circuit 30 will keep the engine running. Then hopefully you can find the source of power into the circuit which is keeping the ignition in the run mode.
Gilly

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Try the OVP.
OVP is power to ECU ign/fuel on HFM/SFI ..could have stuck contacts

In the failed state you could certainly try removing the OVP with the ignition off and see if the car shuts down. I didn't think of that, I was thinking CIS injection, which will run without the control unit at all.....
Gilly

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YES, The Overload Protection Relay was the problem. It must have gotten cooked well the alternator went into overcharge mode.
Thanks for all the Help.

Man....it's amazing how the dreaded OVP is the source of so many problems.

I wonder if the OVP can be blamed for the cause of poverty in third world countries... (j/k).

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".